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排序方式: 共有689条查询结果,搜索用时 17 毫秒
1.
This study assessed the collection efficiency (CE) of two popularly used sampling devices (BioSampler and Coriolis sampler) for fungal aerosols. Phosphate‐buffered saline (PBS) supplemented with or without surfactant (Tween‐20, Tween‐80, or Triton X‐100) and antifoam agent was prepared and used as collection liquids. The agar impactor (BioStage) was simultaneously operated with liquid‐based samplers to collect fungi from seven sites located at a university building, public library, and animal farming. Fungal concentrations determined by liquid samplers were divided by those by BioStage, and the ratio values represented CE. Results indicate that the CE of BioSampler was superior to that of Coriolis (P = 0.0001) and the PBS containing surfactant collected fungi better than that without surfactant (P < 0.0001), whereas antifoam agent showed no influence (P = 0.8). Moreover, fungal concentrations determined by BioSampler with surfactant‐added PBS were statistically indifferent from those by BioStage (P > 0.05) with a Spearman correlation coefficient of 0.81‐0.83 (P < 0.01). In addition to sampler and collection liquid, sampling location was also identified as a significant CE factor (P = 0.006), implying potential influences by fungal genera in the studied fields. Overall, BioSampler with surfactant‐supplemented PBS (eg, Triton X‐100) is recommended considering the great CE and compatibility with a variety of analytical assays. 相似文献
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磷脂是细胞的重要组成成分,对生物体的生长和发育具有重要作用,也是天然的乳化剂、表面活性剂,在食品、医药、化妆品等领域具有广泛的应用。由于每种磷脂分子可以结合不同的脂肪酸,导致磷脂种类繁多且结构复杂,对磷脂的分析比较困难。本文从磷脂的种类及应用、提取纯化、检测方法等方面,对食品中磷脂的研究进展进行概述,比较不同研究方法的优缺点,以期为不同食品中磷脂的深入研究和开发提供参考。 相似文献
3.
茶叶中联苯菊酯、毒死蜱的测定能力验证结果与分析 总被引:1,自引:0,他引:1
目的通过参加能力验证实验,提高实验室农药残留检测的能力。方法优先选择本实验室常用方法,依据NY/T 761-2008、GB/T 23204-2008、GB 23200.13-2016方法,对样品进行相应的提取净化处理,随后根据相应的仪器进行定性定量检测分析,使用仪器比对、方法比对、人员比对、加标回收、质控样品作为质控方法。结果本次能力验证以NY/T761-2008报出检验结果。样品编号为18-U804检测结果为联苯菊酯:0.214 mg/kg, Z比分数为?0.4,毒死蜱为未检出;样品编号为18-Y023检测结果为联苯菊酯为0.582 mg/kg, Z比分数为?0.3,毒死蜱为0.364 mg/kg, Z比分数为?0.6,组织机构判定结果为满意。结论本次能力验证结果为满意,说明本实验室对农药残留的检测能力较好。 相似文献
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A novel non-keyhole friction stir welding technique was proposed to weld the butt joint of 6061-T6 aluminum alloy with the thickness of 6 mm. A sound joint was obtained by this technique, simultaneously eliminating the flash, shoulder mark and keyhole defects. The sleeve directly affected zone (SDAZ) and the sleeve indirectly affected zone (SIAZ) were divided into the joint according to the plunging position of the hollow sleeve. The lack of root penetration defect was avoided when the plunging depth of the hollow sleeve was only 4.2 mm, because the hollow part inside the sleeve improved the material flow below the sleeve. An S-shaped line was left at the SIAZ, and the height of it had the minimum value of 1.47 mm at 20 mm/min. Whether the failure location of the joint was in SIAZ/SDAZ or the heat-affected zone (HAZ) depended on the height and bonding strength of the S-shaped line. The joint fracture location changed from the SIAZ/SDAZ at 35 mm/min to the HAZ at 20 and 30 mm/min. The maximum tensile strength of 224.3 MPa was obtained at 30 mm/min which was 73.7% of that of the base material. The fracture surface morphology exhibited the typical ductile fracture. 相似文献
5.
目的改进气相色谱法测定食品添加剂柠檬酸脂肪酸甘油酯中柠檬酸的分析方法。方法对测定食品添加剂柠檬酸GB 29951-2013《食品安全国家标准食品添加剂柠檬酸脂肪酸甘油酯》的气相色谱法中衍生剂、色谱柱以及升温程序进行优化,并对优化后的方法进行验证。结果选择N,O-双(三甲基硅烷基)-三氟乙酰胺(BSTFA)作为衍生剂,HP-5毛细管柱作为分离柱,温度程序为80℃(1 min)-20℃/min-165℃(5 min)-30℃/min-250℃(1 min),可在15 min内完成对目标物的分离,线性方程为Y=0.67193X+0.05490,r=0.9935,方法回收率为93.0%~98.7%,相对标准偏差(relative standard deviation,RSD)为0.4%,检出限为0.1%。结论该方法目标物分离效果好,回收率及灵敏度高,适用于食品添加剂柠檬酸的定量检测。 相似文献
6.
Tu Ying-Ying Yang Zi-Han Wang Chun-Hao Wang Ting-Wei Lu Fa-Chun 《Journal of the American Ceramic Society》2022,105(8):5240-5251
With high-temperature solid-state reaction method, a series of Lu2Sr(1−x)Al4SiO12:xEu2+ phosphors have been synthesized. With Rietveld refinement method, the crystal structure of Lu2SrAl4SiO12 has been refined. Under the excitation of the ultraviolet and violet band light, Lu2Sr(1−x)Al4SiO12:xEu2+ emits the Eu2+ characteristic blue broadband light. The photoluminescence properties of concentration quenching, emission peak shift, reflectance spectra, and luminescence decay have been investigated. With the structure analyses, the corresponding physical mechanisms have been discussed. With the increased temperature, this phosphor shows well thermal stabilities. For the xEu = 0.06, 0.08, and 0.1 phosphors, the strong anti-thermal quenching performance has been observed. The reason for the anti-thermal quenching of this phosphor has been discussed. The trap capture mechanism may be the suitable physical mechanism to explain the anti-thermal quenching of this phosphor. This phosphor shows the potential applications in the white LED lighting fields. 相似文献
7.
Poly(ethylene terephthalate)/poly(ethylene glycol‐co‐1,3/1,4‐cyclohexanedimethanol terephthalate)/clay nanocomposites: Mechanical properties,optical transparency,and barrier properties 下载免费PDF全文
Poly(ethylene terephthalate) (PET)/clay, PET/poly(ethylene glycol‐co‐1,3/1,4‐cyclohexanedimethanol terephthalate) (PETG), and PET/PETG/clay nanocomposites were fabricated using the twin‐screw extrusion technique. The spherulitic morphologies, thermomechanical, mechanical, and gas‐barrier properties, as well as the effect of clay on the transparency of the resulting nanocomposites were identified. The clay induced the heterogeneous nucleation of the nanocomposites during the cold crystallization process, thereby increasing the crystallinities and melting temperatures of the resulting nanocomposites. The incorporation of clay increased the storage moduli, Young's moduli, impact strengths, and barrier properties of the PET, PETG, and PET/PETG blend. Regarding the optical transparency, the inclusion of clay can make the crystallizable PET matrix crystalline opaque. However, the amorphous PETG maintained its transparency. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39869. 相似文献
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The concept of multitasking workers plays a major role in the success of Just-inTime (JIT) implementation. One key element of a JIT system is its ability to use multitasking workers to react to unbalanced workloads where the bottleneck location changes from period to period. In addition to existing rule-pairs (when to move and where to move), this study develops eight new dynamic dispatching rule-pairs especially for assigning multitasking workers within a JIT production environment. The purpose of this study is to evaluate the performance of these rule-pairs using object-oriented discrete-event simulation and response surface methodology. 相似文献